U.S. Pat. No. 4,997,096 discloses a child-resistant closure having inner and outer plastic shells. The outer plastic shell has a base wall, a peripheral skirt and a circumferential array of lugs on an undersurface of the base wall. The inner plastic shell has a base wall, a peripheral skirt, at least one internal thread segment on the skirt, and a circumferential array of lugs on an outer surface of the base wall for opposed engagement by the internal lugs on the base wall of the outer shell. To remove the closure when it is threaded onto a container neck finish, the outer shell must be pushed axially against the inner shell and simultaneously rotated so that the lugs on the outer shell engage the lugs on the inner shell and rotate the inner shell with respect to the container neck finish. When the outer shell is rotated without applying an axial force to the outer shell, the lugs on the outer shell simply cam over the lugs on the inner shell and do not rotate the inner shell with respect to the container neck finish. Child-resistant closures of this type have been marketed for many years by applicants' assignee under the trademark ARGUS-LOC. See also GB 1529999. A general object of the present disclosure is to provide improvements in child-resistant closures of this type, and to provide packages that include such improved closures.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A child-resistant closure in accordance with one aspect of the present disclosure includes a plastic inner shell having a base wall with a peripheral skirt, at least one internal thread segment on the peripheral skirt and a plurality of internal lugs on the base wall adjacent to the skirt. A plastic outer shell has a base wall with a peripheral skirt and a plurality of internal L-shaped lugs at a juncture of the base wall and the peripheral skirt. Each of the L-shaped lugs includes a first portion extending radially inwardly along an undersurface of the base wall of the outer shell for engaging the external lugs on the inner shell, and a second portion extending axially along an inner surface of the peripheral skirt of the outer shell for slidably engaging the inner shell and aligning the inner shell within the outer shell. The second portions of the L-shaped lugs preferably have rounded radially inwardly facing surfaces for reduced sliding friction with the skirt of the inner shell.
A child-resistant closure in accordance with another aspect of the present disclosure includes a plastic inner shell having a base wall, a peripheral skirt with at least one internal thread segment and an angularly spaced circumferential array of external lugs on the base wall. A plastic outer shell has a base wall, a peripheral skirt and an angularly spaced circumferential array of internal lugs on the base wall. The inner plastic shell is received within the outer plastic shell such that the internal lugs on the base wall of the outer plastic shell are disposed for engagement with the external lugs on the base wall of the inner plastic shell to apply or remove the closure to or from a container neck finish. The internal lugs on the outer shell and the external lugs on the inner shell have opposed rounded axially facing surfaces such that the internal lugs on the outer shell cannot rest on the external lugs of the inner shell upon application of force to the outer shell.
A child-resistant closure in accordance with a further aspect of the present disclosure includes a plastic outer shell having a base wall with a peripheral skirt and a plurality of internal lugs on the base wall adjacent to the skirt, and a plastic inner shell disposed within the outer shell and having a base wall with a peripheral skirt, at least one internal thread segment on the peripheral skirt and a plurality of external lugs on the base wall adjacent to the skirt. The base wall of the outer shell has a peripheral portion of a first thickness on which the internal lugs are disposed and an imperforate central portion of a second thickness less than the first thickness. The base wall of the inner shell has a peripheral portion of a third thickness on which the external lugs are disposed and an imperforate central portion of a fourth thickness less than the first thickness. The thinner central portions of the inner and outer shell reduce the weight and cost of the closure.